Tissue modification devices

ABSTRACT

Described herein are elongate devices for modifying tissue having a plurality of flexibly connected rungs or links, and methods of using them, including methods of using them to decompress stenotic spinal tissue. These devices may be included as part of a system for modifying tissue. In general, these devices include a plurality of blades positioned on (or formed from) rungs that are flexibly connected. The rungs are typically rigid, somewhat flat and wider than they are long (e.g., rectangular). The rungs may be arranged, ladder like, and may be connected by a flexible connector substrate or between two or more cables. Different sized rungs may be used. The blades (on the rungs) may be arranged in a staggered arrangement. A tissue-collection or tissue capture element may be used to collect the cut or modified tissue.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims priority as a divisional of U.S. patentapplication Ser. No. 13/232,882, filed Sep. 14, 2011, titled “TISSUEMODIFICATION DEVICES,” Publication No. US-2012-0065639-A1, which claimspriority as a divisional of U.S. patent application Ser. No. 12/324,147,filed Nov. 26, 2008, titled “TISSUE MODIFICATION DEVICES,” now U.S. Pat.No. 8,192,436, which claims priority as a continuation-in-part of U.S.patent application Ser. No. 11/952,934, filed Dec. 7, 2007, titled“TISSUE REMOVAL DEVICES AND METHODS,” Publication No.US-2008-0147084-A1, now abandoned. U.S. patent application Ser. No.12/324,147 also claims priority to U.S. Provisional Patent ApplicationNo. 61/080,647, filed Jul. 14, 2008 and U.S. Provisional PatentApplication No. 61/081,685, filed Jul. 17, 2008. These applications areherein incorporated by reference in their entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to medical/surgical devices andmethods. More specifically, the present invention relates to flexibletissue modification devices and methods of modifying tissue using suchdevices, particularly for treatment of spinal stenosis.

BACKGROUND OF THE INVENTION

A significant number of surgical procedures involve modifying tissue ina patient's body, such as by removing, cutting, shaving, abrading,shrinking, ablating or otherwise modifying tissue. Minimally invasive(or “less invasive”) surgical procedures often involve modifying tissuethrough one or more small incisions or percutaneous access, and thus maybe more technically challenging procedures. Some of the challenges ofminimally invasive tissue modification procedures include working in asmaller operating field, working with smaller devices, and trying tooperate with reduced or even no direct visualization of the tissue (ortissues) being modified. For example, using arthroscopic surgicaltechniques for repairing joints such as the knee or the shoulder, it maybe quite challenging to modify certain tissues to achieve a desiredresult, due to the required small size of arthroscopic instruments, theconfined surgical space of the joint, lack of direct visualization ofthe surgical space, and the like. It may be particularly challenging insome surgical procedures, for example, to cut or contour bone orligamentous tissue with currently available minimally invasive tools andtechniques. For example, trying to shave a thin slice of bone off acurved bony surface, using a small-diameter tool in a confined spacewith little or no ability to see the surface being cut, as may berequired in some procedures, may be incredibly challenging or evenimpossible using currently available devices.

One area of surgery which would likely benefit from the development ofless invasive techniques is the treatment of spinal stenosis. Spinalstenosis occurs when nerve tissue and/or the blood vessels supplyingnerve tissue in the spine become impinged by one or more structurespressing against them, causing symptoms. The most common form of spinalstenosis occurs in the lower (or lumbar) spine and can cause severepain, numbness and/or loss of function in the lower back and/or one orboth lower limb.

FIG. 1 is a top view of a vertebra with the cauda equina (the bundle ofnerves that extends from the base of the spinal cord) shown in crosssection and two nerve roots branching from the cauda equina to exit thecentral spinal canal and extend through intervertebral foramina oneither side of the vertebra. Spinal stenosis can occur when the spinalcord, cauda equina and/or nerve root(s) are impinged by one or moretissues in the spine, such as buckled or thickened ligamentum flavum,hypertrophied facet joint (shown as superior articular processes in FIG.1), osteophytes (or “bone spurs”) on vertebrae, spondylolisthesis(sliding of one vertebra relative to an adjacent vertebra), facet jointsynovial cysts, and/or collapse, bulging or herniation of anintervertebral disc. Impingement of neural and/or neurovascular tissuein the spine by one or more of these tissues may cause pain, numbnessand/or loss of strength or mobility in one or both of a patient's lowerlimbs and/or of the patient's back.

In the United States, spinal stenosis occurs with an incidence ofbetween 4% and 6% (or more) of adults aged 50 and older and is the mostfrequent reason cited for back surgery in patients aged 60 and older.Patients suffering from spinal stenosis are typically first treated withconservative approaches such as exercise therapy, analgesics,anti-inflammatory medications, and epidural steroid injections. Whenthese conservative treatment options fail and symptoms are severe, as isfrequently the case, surgery may be required to remove impinging tissueand decompress the impinged nerve tissue.

Lumbar spinal stenosis surgery involves first making an incision in theback and stripping muscles and supporting structures away from the spineto expose the posterior aspect of the vertebral column. Thickenedligamentum flavum is then exposed by complete or partial removal of thebony arch (lamina) covering the back of the spinal canal (laminectomy orlaminotomy). In addition, the surgery often includes partial or completefacetectomy (removal of all or part of one or more facet joints), toremove impinging ligamentum flavum or bone tissue. Spinal stenosissurgery is performed under general anesthesia, and patients are usuallyadmitted to the hospital for five to seven days after surgery, with fullrecovery from surgery requiring between six weeks and three months. Manypatients need extended therapy at a rehabilitation facility to regainenough mobility to live independently.

Removal of vertebral bone, as occurs in laminectomy and facetectomy,often leaves the affected area of the spine very unstable, leading to aneed for an additional highly invasive fusion procedure that puts extrademands on the patient's vertebrae and limits the patient's ability tomove. Unfortunately, a surgical spine fusion results in a loss ofability to move the fused section of the back, diminishing the patient'srange of motion and causing stress on the discs and facet joints ofadjacent vertebral segments. Such stress on adjacent vertebrae oftenleads to further dysfunction of the spine, back pain, lower leg weaknessor pain, and/or other symptoms. Furthermore, using current surgicaltechniques, gaining sufficient access to the spine to perform alaminectomy, facetectomy and spinal fusion requires dissecting through awide incision on the back and typically causes extensive muscle damage,leading to significant post-operative pain and lengthy rehabilitation.Thus, while laminectomy, facetectomy, and spinal fusion frequentlyimprove symptoms of neural and neurovascular impingement in the shortterm, these procedures are highly invasive, diminish spinal function,drastically disrupt normal anatomy, and increase long-term morbidityabove levels seen in untreated patients.

Therefore, it would be desirable to have less invasive methods anddevices for modifying target tissue in a spine to help ameliorate ortreat spinal stenosis, while inhibiting unwanted damage to non-targettissues. Ideally, such techniques and devices would reduce neural and/orneurovascular impingement without removing significant amounts ofvertebral bone, joint, or other spinal support structures, therebyavoiding the need for spinal fusion and, ideally, reducing the long-termmorbidity resulting from currently available surgical treatments. It mayalso be advantageous to have minimally invasive or less invasive tissuemodification devices capable of treating target tissues in parts of thebody other than the spine. At least some of these objectives will be metby the present invention.

SUMMARY OF THE INVENTION

Described herein are improved devices for modifying tissue and methodsof using them. These devices may be included as part of a system formodifying tissue. In general, these devices include a plurality ofblades positioned on (or formed from) rungs that are flexibly connected.The rungs are typically rigid, somewhat flat and wider than they arelong (e.g., rectangular). The rungs may be arranged, ladder like, to aflexible substrate, or between two or more cables. Different sized rungsmay be used. The blades (on the rungs) may be arranged in a staggeredarrangement. A tissue-collection or tissue capture element (e.g.,chamber, bag, or the like) may be used to collect the cut or modifiedtissue.

Any of the devices described herein may be used as part of a tissuedecompression (e.g., spinal decompression) method to modify tissue suchas soft tissue (e.g., ligamenum flavum, etc.) and hard tissue (e.g.,bone). In particular, these devices may be used as part of a spinaldecompression technique within a spinal foramen.

The devices described herein may be used as part of a guide-based accessand decompression system, including those previously described in any ofthe following patent applications and provisional patent applications,each of which is herein incorporated by reference in its entirety: U.S.patent application Ser. No. 11/250,332, filed Oct. 15, 2005, titled“DEVICES AND METHODS FOR SELECTIVE SURGICAL REMOVAL OF TISSUE,” now U.S.Pat. No. 7,738,968; U.S. patent application Ser. No. 11/251,199, filedOct. 15, 2005, titled “DEVICES AND METHODS FOR TISSUE ACCESS,” now U.S.Pat. No. 8,192,435; U.S. patent application Ser. No. 11/375,265, filedMar. 13, 2006, titled “METHODS AND APPARATUS FOR TISSUE MODIFICATION,”now U.S. Pat. No. 7,887,538; U.S. patent application Ser. No.11/405,848, filed Apr. 17, 2006, titled “MECHANICAL TISSUE MODIFICATIONDEVICES AND METHODS,” now U.S. Pat. No. 8,430,881; U.S. patentapplication Ser. No. 11/429,377, filed May 4, 2006, titled “FLEXIBLETISSUE RASP,” now U.S. Pat. No. 8,048,080; U.S. patent application Ser.No. 11/538,345, filed Oct. 3, 2006, titled “ARTICULATING TISSUE CUTTINGDEVICE,” Publication No. US-2008-0161809-A1, now abandoned; U.S. patentapplication Ser. No. 11/687,548, filed Mar. 16, 2007, titled “TISSUEREMOVAL WITH AT LEAST PARTIALLY FLEXIBLE DEVICES,” now U.S. Pat. No.8,062,300; U.S. patent application Ser. No. 11/687,558, filed Mar. 16,2007, titled “FLEXIBLE TISSUE REMOVAL DEVICES AND METHODS,” now U.S.Pat. No. 8,062,298; U.S. patent application Ser. No. 11/870,370, filedOct. 10, 2007, titled “PERCUTANEOUS SPINAL STENOSIS TREATMENT,”Publication No. US-2008-0103504-A1, now abandoned; and U.S. patentapplication Ser. No. 12/127,535, filed May 27, 2008, titled “GUIDEWIREEXCHANGE SYSTEMS TO TREAT SPINAL STENOSIS,” now U.S. Pat. No. 8,257,356.

In particular, the devices described herein may use a guidewire-basedsystem that is configured so that the device may be pulled into positionand/or tensioned so as to be urged against a tissue, and thereby modifythe tissue. This configuration may be referred to as a bimanual system,since both ends (e.g., the proximal end and the distal end of thedevice) may be tensioned or pulled to modify the tissue. Tissue may bemodified by removal or smoothing of the tissue, and may be performed bypulling the devices described herein through the tissue so that theworking surface (e.g., the blades on the rungs) contacts one or moretissue surfaces.

In general, the tissue-modification devices described herein have anelongate, flexible body that includes a plurality of connected rungs. Atleast some of the rungs include one or more cutting edges (e.g.,blades), that may project from the rung. The rungs may be connected by aflexible material that extends along the length of the device. Thesedevices are typically configured so that they can be used in the narrowregion of a spinal foramen. Thus, the devices may be substantially flat.For example, the devices may be substantially ribbon-shaped. Thesedevices may also include a distal attachment site for a guidewire. Thus,a guidewire may be used to pull a device from the distal end of thedevice into position, and may also be used to tension the device so thatit is urged against the tissue.

For example, described herein are flexible tissue-modification devicesfor removing tissue from a patient comprising: a flexible elongate bodyhaving an axial length, a width and a thickness. The elongate body inthis example includes a plurality of rungs that are flexibly connected,wherein each rung extends at least partially across the width of thebody. The axial length is greater than the width, and the width isgreater than the thickness, and at least one cutting edge on two or moreof the rungs.

The rungs may be sufficiently rigid that they do not deflect whentension is applied to urge the device against the tissue. For example,the rungs may be formed of a metal, alloy, polymer, or other appropriatematerial(s), particularly those that are relatively rigid.

The elongate body of the device may be formed by the connected rungs,and may be substantially straight (e.g., linear), curved, orsubstantially non-linear in the proximal-to-distal (e.g., along thelength of the device) direction.

The rungs may be shaped as rectangles, squares, ovals, trapezoids, orthe like. In particular, the rungs may have an axial length that is lessthan the width of the rungs. Rungs are typically flat, so that thethickness (or height) of the rungs is less than the width and/or lengthof the rung. Any of these dimensions may vary for different rungs alongthe length of the device. For example, rungs nearer the proximal end maybe thicker, and rungs at either the proximal or distal ends may benarrower or wider.

The rungs may be connected directly to each other, or may be separated.For example, a rung may be directly connected to an adjacent rung via ahinged joint or other movable joint, allowing the device to be flexiblealong its length. In some variations some or all of the rungs areseparated from each other by a spacer. Adjacent rungs may be connectedto each other by one or more connectors. For example, a connector may bea flexible connector such as a mesh or woven material. As mentioned, theconnector may be a hinged joint. In some variations, the connectorcomprises at least one cable.

Any of the tissue modification devices described herein may include oneor more guidewire couplers at the distal end of the device. A guidewirecoupler typically engages with a portion (e.g., the proximal end) of theguidewire to secure the guidewire to the guidewire coupler. Theguidewire coupler may be configured so that a portion of the guidewire(such as the proximal end of the guidewire) is held securely in thedistally located guidewire coupler. The guidewire coupler may releasablyhold the guidewire in position. The guidewire is typically held by theguidewire coupler so that when engaged, the guidewire and the guidewirecoupler do not move relative to each other. Additionally, the guidewiremay be typically held so that pulling on the distal end region of theguidewire results in pulling the device from its distal end, i.e.pulling the device from where the guidewire is coupled via the guidewirecoupler. Thus, the coupler may engage the guidewire with sufficientstrength and stability to allow the device to be positioned within thebody by drawing on the distal end of the guidewire.

The tissue modification devices (or systems including the devices) mayalso include a handle or a handle attachment region at the proximal endof the device. A handle may be for manual manipulation (e.g., pulling)of the device. The handle may be removable or non-removably attached tothe device.

In some variations, the devices also include at least one protectiveside guard extending along the length of the flexible elongate body. Theprotective side guard may be a shield or barrier that prevents the edgesof the device (e.g., the edges of the rungs) from scraping tissue as thedevice is drawn proximally/distally, particularly when modifying tissue.For example, the protective side guard may be a polymeric (e.g.flexible) material having a smooth, atraumatic outer surface.

As mentioned, any of these devices may also include at least one spacerbetween adjacent rungs. A spacer may be a ball, tube, washer, or thelike. The spacer may be any appropriate size, to provide an appropriatedistance between adjacent rungs. In some variations multiple spacers areused between rungs. For example, multiple spacers may be placed on thesides of the rungs. In some variations, the spacers are linked to therest of the device by a hollow or passage. For example, a spacer may bethreaded between rungs on the connector(s) linking the rings. A spacermay also attach to other structures. For example, in variations in whicha collection region is provided, the spacer may connect to a collectionbag.

One or more cutting edges may be included on each rung. The cutting edgemay be part of a blade. In some variations of the tissue modificationdevices, the cutting edge(s) on the rung or rungs project from thesurface of the rung. For example, a blade may be formed by a portion ofthe rung that extends up (e.g., out of the plane of the tissuemodification device). The blade or cutting edge may be oriented so thatit optimally cuts tissue as the device is urged against the targettissue. For example, the blade may be oriented so the blade isperpendicular to the long axis (the length) of the device. The blade maybe shaped (e.g., flat, pointed, or the like). The shape and orientationof the blade may help steer the device as it is urged against thetissue.

Cutting edges may be arranged on the device (e.g., on any of the rungs,or any plurality of rungs) in any appropriate manner. For example,cutting edges (e.g., blades) may be arranged so that there are more orfewer blades in some regions than in others. In some variations, thedensity of cutting edges increases along the length of the tissuemodification device such that there are fewer cutting edges near thedistal end of the device, and the number of blades increases along thelength, proceeding proximally; the number or density (distribution) ofblades may then decrease again towards the proximal end of the regionthat will engage the tissue. In general, the descries described hereinmay be used as two stroke devices, so that the device may modify tissueboth as it is drawn distally (e.g., forward) and as it is drawnproximally (backwards). Thus, the tissue modification device may beadapted to modify tissue in both directions. Alternatively, in somevariations, the device may be adapted so that it does not substantiallymodify tissue when drawn in one direction, but only when moved in theopposite direction. For example, cutting edges may be shielded orprotected on one side by including a blunting region.

The cutting edges on adjacent rungs of the tissue modification devicemay be axially offset from each other. Offsetting the axial position ofthe blades (or cutting edges) may enhance cutting by presenting a widereffective cutting surface. Thus, relatively narrow (or pointed)blades/cutting edges may be used to cut a region of tissue that is widerthan the blade/cutting surface width.

The cutting edge may generally be positioned on the rung (and thereforeon the device) so that it is not immediately adjacent to the edges ofthe device. For example, the cutting edge may be positioned on the rungspaced from the edge of the rung. For example, the cutting edge may bespaced approximately 0.5 mm, or greater than 0.5 mm.

In some variations the tissue modification devices may include blades ofdifferent shapes and sizes on the same device. Blades may have differentheights (e.g., projecting from the rung), widths, shapes, etc. Differentshaped/sized blades may also be arranged along the length of the tissuemodification device (e.g., along the tissue modification surface or sideof the device). For example, in some variations, blades at the moreproximal end of the tissue modification device may be more closelyspaced and may have a lower profile than blades more distally.Alternatively, the blades near the ends (e.g. proximal and distal ends)of the tissue modification region of the device may be less closelyspaced and have a slightly higher profile than blades along the centerof the length of the device. These arrangements may help overcomestiction when using the device to modify tissue. For example, the tissuemodification device could have blades with graduated profiles so thatthe blades near the ends (proximal and distal) permit a “running start”for the tissue modification from the larger blades. In some variations,the profile of the blades near one or both ends (e.g., the distal end)have a lower profile than blades near the middle of the tissuemodification device

In some variations, the tissue modification device may also include oneor more ramps or projections that are not cutting edges, that projectfrom one or more of the rungs. Ramp regions may project from one or morerungs and may have increasing profile(s) towards the center of thetissue modification region. A ramp or ramp region may dilate the regionto be modified. In some variations the maximum height of the ramp may bethe same or slightly greater than the height of any blades.

Any of the devices described herein may also include a tissue collectionregion for collecting tissue cut by the device. The tissue collectionregion may communicate with the rungs, so that it forms behind the rungs(e.g., away from the cutting face of the device). Examples of tissuecollection regions are described in greater detail below, but may beconfigured so that they have a fixed minimum volume. Tissue may enterthe tissue collection region by passing through or around the rungs. Forexample, in variations in which the rungs are spaced apart, tissue maypass into the tissue collection region by passing between the rungs. Insome variations the rungs include one or more channels or passages thatmay guide tissue into the tissue collection region. The tissuecollection region may be removable (e.g., to empty or swap out whenfull), replaceable, or emptyable, so that the device can be re-used orused after emptying the tissue collection region.

Also described herein are flexible tissue-modification devices forremoving tissue from a patient that include at least two flexibleelongate cables, wherein the cables extend substantially adjacent toeach other from the proximal end of the device to the distal end of thedevice, a plurality of rungs, wherein each rung extends between thecables, and at least one cutting edge on two or more of the rungs. Anyof the features described above may be included in this variation aswell. For example, the width of a rung extending between the flexibleelongate cables may be greater than the length of that rung extendingproximally to distally.

In variations in which the rungs are connected via a connector such as aplurality of cables, the distal ends of such flexible elongate cablesmay be secured together. Similarly, the proximal ends of the flexibleelongate cables may also (or alternatively) be secured together.

Also described herein are methods of modifying tissue. For example, insome variations, the methods include the steps of: passing a flexibletissue-modification device at least partially around a target tissue,wherein the flexible tissue-modification device is configured as any ofthe flexible tissue-modification devices described herein (e.g.,comprises a flexible elongate body having a width and a thickness, aplurality of rungs that are flexibly connected, wherein each rung atleast partially extends across the width of the body, and at least onecutting edge on two or more of the rungs); moving thetissue-modification device against the target tissue by pulling thetissue-modification device from at least one end of the device; andcutting the target tissue with the cutting edges on the rungs of thetissue-modification device.

The step of passing the flexible tissue-modification device at leastpartially around the target tissue may include passing a guidewire atleast partially around the target tissue and pulling the flexibletissue-modification device around the target tissue using the guidewire.

In some variations, the method also includes collecting cut tissue intoa tissue collection portion of the tissue-modification device.

In any of the methods described herein, the tissue may be modified todecompress one or more spinal nerves. For example, the method mayinclude the steps of removing or modifying tissue within a spinalforamen.

The step of moving the tissue-modification device against the targettissue may include applying tension to both the proximal end and thedistal end of the tissue-modification device to drive thetissue-modification device against the target tissue. The method mayalso include the step of detecting neuronal tissue near the flexibletissue-modification device. For example, one or more electrodes may beused to determine the proximity of a nerve to the cutting surface(s) ofthe device.

Any of the methods described herein may include a step of sensing achange in the tissue type (e.g., from hard to soft tissue) duringoperation. For example, the method may include the step of sensing achange in the resistance to movement. In general, the tactile feel ofthe tissue being cut may change between hard and soft tissues, and thisfeel may be sensed either automatically (using one or more sensors thatare sensitive to changes in resistance to motion of the device) ormanually (e.g., a user may feel more of a “kick”).

As mentioned, any of the devices described herein may include a tissuecollection region. In particular, tissue collection regions having afixed open volume or a fixed minimum open volume are described. Forexample, described herein are flexible tissue-modification devices forremoving tissue from a patient, comprising: a flexible elongate bodyextending proximally and distally along a length, further having ananterior surface, wherein the anterior surface extends at leastpartially proximally and partially distally; a plurality of cuttingedges communicating with the anterior surface; and a tissue collectionregion configured to store tissue cut by the plurality of cutting edges,the tissue collection region having a fixed minimum open space and oneor more vias allowing tissue cut from the cutting edge into the openspace, wherein the open space of the tissue collection region is formedbetween the anterior surface and a posterior substrate separated fromthe anterior surface by a thickness.

A minimum open space may allow tissue to be driven into the tissuecollection region without requiring substantial force. Thus, in somevariations the device is configured so that the minimum open volumeformed as the space between the anterior surface and the posteriorsubstrate (which forms a second surface) is relatively constant evenwhen the devices are flexed along their length as they are pulledagainst a target tissue (e.g., within a spinal foramen). The minimumopen volume may be determined by the size of the opening. For example,the anterior surface and the posterior surface formed by the posteriorsubstrate may be separated by a minimum distance of between about 0.5 mmand about 5 mm.

The posterior substrate may be secured in parallel to the anterior(tissue cutting) surface. In some variations, the posterior substrate isa relatively rigid elongate substrate extending at least partiallyproximally and partially distally. The posterior substrate may extendthe same distance as the anterior surface, so that the tissue collectionregion underlies all of the cutting edges. In some variations, theposterior substrate is formed so that it does not inhibit the flexing orbending (the flexibility) of the elongate body. In some variations, theposterior substrate is foamed of an expandable material that allows theposterior substrate to expand as the tissue collection region is filled.

The posterior substrate may be coupled to the anterior surface. Forexample, the posterior substrate may be coupled to the anterior surfaceby a plurality of connectors linking the anterior surface to theposterior substrate. The connectors may be rigid, to maintain theminimum open volume. In some variations, the posterior surface isconnected to the device so that it may be extendable in theposterior/anterior direction, along the length of the device. The devicemay be configured so that the posterior surface moves along the length(proximally/distally) as the device is flexed. For example, theposterior substrate may be extendable in the proximal and distal axis.For example, the posterior substrate may be coupled to the flexibleelongate body by an expandable connector that allows the posteriorsubstrate to extend or contract proximally and distally as thetissue-modification device is flexed. The expandable connector may be aspring, an elastic region, or the like.

In some variations, the posterior substrate comprises an accordionregion, which may expand/contract as it is flexed. The expansion mayoccur along the length of the device. In some variations, the posteriorsubstrate may expand open to increase the volume of the tissuecollection region above the minimum open volume. In some variations thevolume of the tissue collection region is relatively constant (and isapproximately fixed minimum open volume).

The plurality of cutting edges may be blades, and these cutting edgesmay project from the anterior surface.

A via through which tissue may pass into the tissue collection regionmay be an opening or a channel through the anterior surface. Forexample, a via may be a channel formed at the base of a cutting edge orblade. In some variations the via is an opening formed in the anteriorsurface which is adjacent to the blade extending from the anteriorsurface.

As described above, in some variations the device includes a pluralityof connected rungs. Thus, the anterior surface may comprise a pluralityof rigid rungs that are flexibly connected.

Any of the device variations including a tissue collection region havinga fixed minimum open space or volume may include a guidewire attachmentregion, as mentioned above, and/or a handle or handle attachment regionin communication with the proximal end of the flexible elongate body.

For example, in some variations a device for modifying tissue is aflexible elongate tissue-modification device including: a flexibleelongate body having a length and a width, the body extending distallyand proximally along the length, wherein the length is greater than thewidth; a plurality of rungs that are flexibly connected, wherein eachrung extends across the width of the body; at least one cutting edge ontwo or more of the rungs; and a tissue collection region adjacent to therungs, wherein the tissue collection region has a minimum open spacedefined by the space between the rungs and a tissue collection substratethat extends at least partially proximally and distally. The tissuecollection region comprises a plurality of connectors connecting thetissue collection substrate with the rungs.

Also described herein are methods of removing tissue from a patient, themethod comprising: passing a flexible tissue-modification device havinga tissue collection region at least partially around a target tissue,wherein the flexible tissue-modification device comprises a flexibleelongate body having an anterior surface extending proximally anddistally, a plurality of cutting edges communicating with the anteriorsurface and a tissue collection region having a minimum open space incommunication with the cutting edges; moving the tissue-modificationdevice against the target tissue by pulling the tissue-modificationdevice from at least one end of the device; cutting the target tissuewith the cutting edges; and collecting the cut tissue into the openspace of the tissue collection region. The step of passing the flexibletissue-modification device at least partially around the target tissuemay include passing a guidewire around the target tissue, and pullingthe flexible tissue-modification device around the target tissue usingthe guidewire. These methods may also be used to decompress spinaltissue. For example, the target tissue may comprise tissue within aspinal foramen.

The step of moving the tissue-modification device against the targettissue may include applying tension to both the proximal end and thedistal end of the tissue-modification device to drive thetissue-modification device against the target tissue.

In some variations, the method also includes the step of sensingneuronal tissue near the flexible tissue-modification device.

In some of the tissue-modification devices described herein, the deviceshave a first configuration and can be converted to and locked in asecond configuration. The first and second configurations may refer tothe configuration of the devices in the proximal-distal axis. The firstconfiguration may be linear (e.g., relatively un-curved) and the secondconfiguration may be curved or bent. In both configurations (the firstand second), the device may still be flexible along its length (e.g.,proximally to distally) in at least one direction (e.g.,anterior/posterior).

For example, a flexible tissue-modification device for removing tissuefrom a patient may include: a flexible elongate body having a length, awidth and a thickness, wherein the length is greater than the width, andthe width is greater than the thickness, an anterior surface extendingproximally and distally across the width of the flexible elongate body;a plurality of cutting edges communicating with the anterior surface,wherein the flexible tissue-modification device is convertible from afirst configuration, in which the anterior surface has a first proximalto distal shape, and a second configuration in which the anteriorsurface has a second proximal to distal shape; and a lock for lockingthe proximal to distal shape of the anterior surface of thetissue-modification device.

The device may also include a cable extending proximally and distally inthe device that is configured to change the proximal to distal shape ofthe anterior surface when tension is applied to the cable. As mentioned,the first proximal to distal shape of the anterior surface may belinear. The second proximal to distal shape of the anterior surface maybe bent or curved. For example, the second proximal to distal shape maybe C-shaped, S-shaped, etc.

As mentioned, any of these devices may include a guidewire coupler atthe distal end of the flexible elongate body, and/or a handle or handleattachment region in communication with the proximal end of the flexibleelongate body. As described above, the anterior surface may include aplurality of flexibly connected rungs, wherein each rung extends acrossthe width of the flexible elongate body. Any of these devices may alsoinclude a tissue collection region, particularly a tissue collectionregion having a fixed minimum space.

For example, described herein are flexible tissue-modification devicesfor removing tissue from a patient that include a flexible elongate bodyhaving a length, a width and a thickness, wherein the length is greaterthan the width, and the width is greater than the thickness; a pluralityof rungs that are flexibly connected, wherein each rung extends acrossthe width of the body and forms an anterior surface; at least onecutting edge on two or more of the rungs; wherein the flexibletissue-modification device is convertible from a first configuration, inwhich the anterior surface has a first proximal to distal shape, and asecond configuration, in which the anterior surface has a secondproximal to distal shape; and a lock for locking the proximal to distalshape of the anterior surface of the tissue-modification device.

The devices described herein may also include a cable extendingproximally and distally in the device that is configured to change theproximal to distal shape of the anterior surface by applying tension tothe cable.

Methods of removing tissue from a patient may include using tissuemodification devices that can be converted between differentproximal-to-distal shapes, such as those described above. For example,described herein are methods of removing tissue from a patientcomprising: passing a flexible tissue-modification device at leastpartially around a target tissue, wherein the flexibletissue-modification device comprises a flexible elongate body having ananterior surface extending proximally and distally, and a plurality ofcutting edges communicating with the anterior surface; wherein theanterior surface of the flexible tissue-modification device isconvertible between a first proximal to distal shape and a secondproximal to distal shape; converting the anterior surface of the tissuemodification device from a first proximal to distal shape to a secondproximal to distal shape; locking the anterior surface in the secondproximal to distal shape; moving the tissue-modification device againstthe target tissue by pulling the tissue-modification device from atleast one end of the device; and cutting the target tissue with thecutting edges.

The step of converting the anterior surface of the tissue modificationdevice from a first proximal to distal shape to a second proximal todistal shape may include converting the anterior surface from a linearshape to a curved shape, such as a C-shape or an S-shape, or the like.

In some variations, the step of passing the flexible tissue-modificationdevice at least partially around the target tissue comprises: passing aguidewire around the target tissue; and pulling the flexibletissue-modification device around the target tissue using the guidewire.

Any of the methods for modifying tissue, including the methods in whichthe tissue modification device changes shape, may include collecting cuttissue by the cutting edges of the tissue-modification device into atissue collection portion of the tissue-modification device.

The step of moving the tissue-modification device against the targettissue typically comprises applying tension to both the proximal end andthe distal end of the tissue-modification device to drive thetissue-modification device against the target tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top view of a vertebra with the cauda equina shown in crosssection and two nerve roots branching from the cauda equina to exit thecentral spinal canal and extend through intervertebral foramina oneither side of the vertebra.

FIG. 2A is a partially exploded, perspective view of a flexible tissuemodification device including a plurality of flexibly connected rungs.

FIG. 2B is a perspective view of another variation of a tissuemodification device with progressively larger and smaller bladesarranged along the length.

FIG. 2C is another variation of a tissue modification device.

FIG. 2D is another variation of a tissue modification device includingtwo ramp regions.

FIG. 3A shows one variation of a distal end of a tissue modificationdevice, including a guidewire coupler.

FIG. 3B shows another variation of the distal end of a tissuemodification device, including a guidewire coupler.

FIG. 4 shows a partial perspective view of a region of a tissuemodification device.

FIG. 5A is a partial perspective view of another region of a tissuemodification device.

FIG. 5B is a partial perspective view of another variation of a tissuemodification device.

FIG. 6 shows one variation of flexibly connected rungs of a tissuemodification device.

FIG. 7 shows another variation of flexibly connected rungs of a tissuemodification device.

FIG. 8A shows another variation of flexibly connected rungs of a tissuemodification device, and

FIG. 8B illustrates the bending of the flexibly connected rungsillustrated in FIG. 8A.

FIG. 9A shows a flexible material that may be used as a connector toconnect rungs forming a tissue modification device.

FIG. 9B illustrate one variation of a rung that may be used with theconnector shown in FIG. 9A.

FIG. 9C illustrates the attachment of the rung of FIG. 9B onto thematerial of FIG. 9A, and

FIG. 9D shows the rung assembled on the connector material.

FIG. 9E shows an alternative attachment of the rung of FIG. 9B onto amaterial such as the connector material of FIG. 9A, and

FIG. 9F shows a bottom view of the rung and connector assembly of FIG.9E.

FIG. 9G is a partial perspective view of one variation of a tissuemodification device.

FIG. 9H is a side cross-section through the tissue modification deviceof FIG. 9G.

FIG. 10 is a bottom view of a tissue modification device includingprotective side covers.

FIG. 11 is a top view of a tissue modification device includingprotective side covers.

FIG. 12A is a side view of one variation of a tissue modification deviceincluding a fixed minimum open volume tissue collection region.

FIG. 12B is a cross-sectional view through the tissue modificationdevice of FIG. 12A.

FIG. 12C is a top view of the tissue modification device of FIG. 12A.

FIG. 12D shows a partial perspective view of a portion of a tissuemodification device.

FIG. 12E is a top view of the tissue collection region of FIG. 12D.

FIGS. 12F and 12G illustrate sections through the device shown in FIG.12D.

FIG. 13A shows one variation of a substrate of a tissue collectionregion such as the one shown in FIG. 12A-12C.

FIGS. 13B1-13B3 illustrate one variation of a substrate for a tissuecollection region in which the substrate may accordion.

FIG. 14A shows another variation of a substrate for a tissue collectionregion having expandable regions and semi-rigid regions, and

FIG. 14B is a top view of a semi-rigid frame for a tissue collectionregion such as the one in FIG. 14A.

FIG. 15A is a cross-section through another tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 15B shows a partial side view of a tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 15C is a cross-section through another tissue modification devicehaving a fixed minimum open volume tissue collection region.

FIG. 16A shows perspective views of two adjacent rungs havingalternating tissue cutting edges or blades, and

FIG. 16B shows a side view of both of the two rungs illustrated in FIG.16A.

FIG. 16C shows a side view of the two rungs shown in FIGS. 16A and 16Bwhen the two rung has been positioned adjacent to each other.

FIG. 17A shows one variation of a tissue modification device having anon-linear axial shape.

FIGS. 17B-17C illustrate one variation of a tissue modification devicethat may be expanded from a first, narrower, configuration (shown inFIG. 17B), into a second, wider, configuration (shown in FIG. 17C).

FIGS. 17D-17E illustrate another variation of a tissue modificationdevice that may be expanded from a first, narrower, configuration (shownin FIG. 17D), into a second, wider, configuration (shown in FIG. 17E).

FIG. 18 is a partial perspective view of a flexible tissue modificationdevice having a non-linear axial shape.

FIG. 19A is a posterior view of the spine indicating decompression pathsat disk level and along the nerve root.

FIG. 19B is a posterior view of the spine indicating a decompressionpath for adjacent level lateral recess decompression.

FIG. 19C is a posterior view of the spine indicating a decompressionpath for central canal decompression.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of tissue modification devices and systems, as wellas methods for making and using tissue modification devices and systems,are provided herein. In general, a flexible tissue-modification deviceas described herein is configured to remove tissue from a patient. Inparticular, these tissue-modification devices may be configured todecompress spinal stenosis. These devices typically include a flexibleelongate body that extends proximally to distally (proximal/distal), andis configured to be inserted into a patient so that it extends aroundthe target tissue, so that it can be bimanually pulled against thetarget tissue by applying tension to either end of the device. Thus, thedevice may be extended into, through, and/or around a spinal foramen.The device is flexible in at least one plane. For example, in variationsin which the device has an elongated ribbon shape that is long and flatwith a width greater than the thickness, the device includes a firstmajor surface (e.g., a front) and a second major surface (a back), andhas edges (minor surfaces) between the first and second major surfaces.The first major surface may be referred to as the anterior or frontsurface and the second major surface may be referred to as the posterioror back surface. The devices described herein may be flexible along theanterior and posterior surfaces, and the anterior or front surface mayinclude one or more cutting edges configured to cut tissue as theanterior surface of the device is urged against a tissue. The posteriorsurface may be configured to shield or protect non-target tissue.

The tissue modification devices described herein also typically includeone or more of the following features: all or a portion of the devicemaybe formed of flexibly connected rungs or links; the devices mayinclude a tissue capture region having a fixed minimum volume; and thedevice may be configured so that the major/minor surfaces may havenon-linear shapes along their length, or may be stitched between linearand non-linear shapes. A tissue modification device may include one ormore of these features in any combination. Each of these features isdescribed and illustrated in greater detail below.

Although much of the following description and accompanying figuresgenerally focuses on surgical procedures in spine, in alternativeembodiments, devices, systems and methods of the present invention maybe used in any of a number of other anatomical locations in a patient'sbody. For example, in some embodiments, the flexible tissue modificationdevices of the present invention may be used in minimally invasiveprocedures in the shoulder, elbow, wrist, hand, hip, knee, foot, ankle,other joints, or other anatomical locations in the body. Similarly,although some embodiments may be used to remove or otherwise modifyligamentum flavum and/or bone in a spine to treat spinal stenosis, inalternative embodiments, other tissues may be modified to treat any of anumber of other conditions. For example, in various embodiments, treatedtissues may include but are not limited to ligament, tendon, bone,tumor, cyst, cartilage, scar, osteophyte, inflammatory tissue and thelike. Non-target tissues may include neural tissue and/or neurovasculartissue in some embodiments or any of a number of other tissues and/orstructures in other embodiments. In one alternative embodiment, forexample, a flexible tissue modification device may be used to incise atransverse carpal ligament in a wrist while inhibiting damage to themedian nerve, to perform a minimally invasive carpal tunnel releaseprocedure. Thus, various embodiments described herein may be used tomodify any of a number of different tissues, in any of a number ofanatomical locations in the body, to treat any of a number of differentconditions.

Flexibly Connected Rungs

In some variations, a tissue modification device is formed from aplurality of flexibly connected rungs. As used herein, a rung may alsobe referred to as a link or crosspiece. A rung may be stiff (e.g., madeof a relatively rigid material) or flexible. The rungs may be connectedto or may form the anterior (front) major surface. At least some ofthese rungs include one or more cutting edges, which may be configuredas blades. The cutting edges may be formed as part of the rung, orattached to the rung.

Individual rungs may have any appropriate shape. For example, a rung mayhave a rectangular shape, an oval shape, a trapezoidal shape, or thelike. In general, the rung is relatively flat (e.g., having a thicknessthat is substantially less than the length and width). A rung may besmooth, rough or some combination. Different rungs in the same devicemay be different shapes and sizes, as illustrated below. A rung may bedirectly or indirectly connected to adjacent rungs.

Rungs are flexibly connected to adjacent rungs and/or to another portionof the tissue modification device. A connector, such as a cable, wire,chain, string, sheet, ribbon, mesh, fabric, or the like, may be used toconnect adjacent rungs. The connector may be flexible, or stiff. Aconnector may extend only between adjacent rungs, or it may extend alongall or a portion of the length of the device so that multiple rungs maybe attached to the same connector. More than one connector may be usedto connect adjacent rungs. For example, rungs may be connected betweentwo parallel wires. In some variations, the rungs are directly connectedto adjacent rungs by a hinge joint or the like. Combinations ofconnectors and direct connections between rungs may be used.

In some variations, rungs may be separated from each other by a space.The space may be an opening. In some variations, one or more spacers areused to separate adjacent rungs. The spacing between adjacent rungs maybe different. In variations including one or more tissue collectionregions, the spaces between rungs may provide a passage (or via) betweenthe cutting surface on the anterior-facing surface of the rung, on whicha cutting edge may be located (or may extend from) and the tissuecollection region.

For example, FIG. 2A illustrates one variation of a tissue modificationdevice having a plurality of rungs. FIG. 2A is a partially exploded,perspective view illustrating enlargements of various regions. Thetissue-modification device shown in FIG. 2A is flexible and includesindividual rungs that may articulate relative to each other. This deviceincludes two parallel cables 201, 201′ and a plurality of rungs 205,205′, 206, 203 extend between the cables. The cables are the connectorsthat link adjacent rungs. In this example, the two cables are joined atthe proximal 233 and distal 235 regions. In some variations, the cableis joined at the proximal and distal ends, or is formed from a singlecable; in some variations the two cables are separate. At least aportion of the cable is flexible. Any appropriate cable may be used,including metal or polymeric cables. Cables may be single-filament orformed of multiple filaments. The portion of the cable towards thedistal end of the device, as shown in this example, may be hinged, andthe links between distal and proximal sections may be connected inflexible junctions.

In some embodiments, the links or rungs 205, 205′, 206, 203 spanning thecables have different shapes and sizes. The rungs 203 in the centralregion each include one or more cutting edges 211 projecting from theanterior (target tissue facing) surface. These cutting rungs 203 mayform a tissue modifying region of the device. The cutting edges shownare triangular or pointed, although any appropriate shape may be used.Further, these cutting edges may be oriented in any desired manner; theorientation of the cutting edges may help steer or guide the device asit is urged against a target tissue to cut the tissue. In this examplethe cutting edges are oriented in parallel with the long axis (thedistal/proximal axis) of the device.

In some embodiments, the rungs may have varying widths along the lengthof the tissue modification device. For example, the rungs toward thedistal end of the device may have a small width, while rungs towards theproximal end of the device may have a larger. For example, the smallwidth may be on the order of 4 to 6 mm, while the large width may be onthe order of 6 to 8 mm. Thus, there may be an intermediate region alongthe length of the tissue modification device over which the width of thedevice (approximately the width of the rungs in some variations)transitions from relatively narrow to relatively wider. In someembodiments, there may be rungs of a medium width in the center portionof the device. These transition rungs may include cutting edges or mayalternatively be non cutting rungs.

In one variations, as shown in FIG. 2B, the cutting edges may havedifferent heights on different rungs. For example, in FIG. 2B thecutting edges on the rungs toward the center of the device 298 may havea first height, while the cutting edges on the rungs toward the proximal299 and/or distal 299′ ends of the device may have a second height. Thefirst height may be larger than the second height, allowing the deviceto cut first a shallow cut, and then a deeper cut as the device ispulled along against tissue. The cutting edges in this configuration mayfunction to provide a smooth transition as the device is pulled alongagainst tissue and the sequentially higher cutting edges begin to engagewith the tissue. Alternatively, the second height may be larger than thefirst height.

In some variations, the cutting edges are formed from the materialforming the rung, and the cutting edge (e.g., blade) is machined as partof the rung. For example, a rung may have an initial thickness measuringthe height of the rung and the blade. The material at this initialthickness is machined (or otherwise removed) to form a series of bladesprojecting from the surface of the rung. Alternatively, the cuttingedges may be cut out of the surface of the rung, and bent out of thesurface of the rung such that the cutting edge or blade is substantiallyperpendicular to the rung. The cutting edge may be cut by Wire EDMmachining (Electrical Discharge Machining), or any other suitableprocess. In some embodiments, the cutting edges or blades may bemanufactured separately and connected to the rung.

In FIG. 2A the rungs are threaded onto the cables by openings orchannels formed in the rung. For example, a tissue-modification devicesuch as the one shown in FIG. 2A may be formed by threading the variouscomponents (e.g., rungs, spacers, etc.) onto the cable(s) connectingthem. In some variations (described in greater detail below), a tissuecollection region may be connected below the rungs. In some variationsthe rungs may be rings, or may include space for tissue collection or atissue-collection region.

In some embodiments, as shown in FIG. 2C, crimping elements 272, 272′may also be threaded onto the cables by openings or channels formed inthe crimping elements. Once in place, the elements may be crimped to thecable or fixed to the cable in any other suitable fashion, such as bywelding. The crimping elements fixed to the cable function to hold therungs and other various components in place, and may further function toavoid loading the proximal and/or distal portions and/or ends of thetissue modification device.

The cables or rungs in one or more regions along the device may becovered or protected. For example, in FIG. 2C, the proximal portions ofthe tissue modification device includes a protector region, such as asolid material or covering element over the cables. Thus, the tissuemodification device may have a solid proximal end protector region orportion 274. This solid portion may be a polymer extrusion, or any othersuitable material in any suitable configuration.

A widener or ramp region or regions may also be included as part of thetissue modification device. For example, FIG. 2D shows one variation ofa tissue modification device having ramp regions 288, 288′ at theproximal and distal portions of the tissue modification device. In someembodiments, the ramp begins towards the proximal and/or distal ends ofthe device, at a height approximately flush with the device, andincrease. For example, the height may increase to approximately theheight of any blades or cutting surfaces, or slightly higher. In someembodiments, the height of the ramp increases to a height approximatelyequal to or just below the height of the blades. The ramp may functionto provide a smooth transition as the device is pulled along againsttissue and the cutting edges begin to engage with the tissue. The rampmay extend across multiple rungs, a single rung, or may be coupled tothe cables of the device. The ramp may be a solid structure, or a ribbedstructure (as shown in FIG. 2D).

Rungs 203 with cutting edges 211, may extend over a portion of thelength of the device. As illustrated in FIG. 2A, the device may includetwo or more rungs with cutting edges or blades 203 (e.g., “cuttingrungs”). In this example, these cutting rungs 203 are separated by a gapformed by spacing elements 209 between the rungs. These spacing elementsare also attached to the connector 201, 201′ that flexibly connects therungs. In FIG. 2A the spacers are threaded on the two parallel cables.The sizes of the connectors and/or spacing elements 209 may be varied tochange the spacing between the rungs, and also the longitudinal shape(curvature) of the device, as described in greater detail, below.

In addition to the cutting rungs 203, other rungs may also be includedthat do not have a cutting surface. For example, linking rungs 205, 205′may be used. In FIG. 2A distal linking rungs 205 are shown removed fromthe device, but may be included. These rungs may protect the cable,and/or the tissue, and may be different sizes. Nearer to the distal end235 of the device shown in FIG. 2A, smaller rungs 206 may be used tohouse the cable or cables connecting the rungs. These rungs 206 may beshaped to allow the device to be flexible in one or more direction(e.g., up/down relative to the major surface), while limiting theflexibility in other directions.

In some embodiments, the cutting rungs, non-cutting rungs, spacingelements, or any other suitable portion of the device may include atracking element. For example, a tracking element may be disposed in thedistal end of the device, such that the tip of the device may be trackedas it is inserted into a patient and/or moved within the patient.Alternatively, the device may include multiple tracking elementsdisposed along the length of the device, or multiple tracking elementsdisposed along a portion of the length of the device (for example alongthe cutting region of the device). In some embodiments, the trackingelement is a material that is detectable by an imaging system. Someexamples of suitable tracking elements include echogenic materials orsubstances (i.e. configured to form an echogenic surface) detectable byan ultrasound system, and radio-opaque materials detectable by aradiograph system, such as a fluoroscope. Alternatively, the trackingelement may be configured to be detectable by an MRI or Infrared system.In some embodiments the tracking element is preferably a coil configuredto be detected by an electromagnetic tracking or navigation system. Forexample, the devices described herein may incorporate a tracking systemsuch as the AXIEM™ Electromagnetic Tracking Technology, e.g., theStealthStation® AXIEM™ (Medtronic Navigation, Louisville, Colo. USA). Insome embodiments, the device is configured to generate anelectromagnetic field around a patient's target anatomy that can betracked to triangulate the positioning of devices having trackingelements.

The proximal end 233 of the device shown in FIG. 2A includes a handle231 which may be permanently or removeably attached to the proximal end.The distal end 235 shown in FIG. 2A includes a guidewire coupler 237that is flexibly attached to the distal end of the device. A guidewirecoupler is configured to attach to a guidewire (e.g., one end of aguidewire) so that the device can be manipulated, at least in part, bypulling on the guidewire after the guidewire has been secured to thedevice. For example, in some variations a guidewire may be inserted intothe body from a first location outside of the body, then passed aroundthe target tissue (e.g., around a spinal foramen) and out of the bodyfrom a second position. The distal end of the guidewire may then becoupled to the flexible tissue modification device (such as the oneshown in FIG. 2A) and pulled through the body until the tissue modifyingregion of the device, e.g., the portion of the device including cuttingrungs 203, is positioned opposite the target tissue. In some variationsthe guidewire used includes a tip region that is enlarged and may engagethe guidewire coupler. For example, the guidewire may have a proximalend with a flange or ball. This enlarged region may be configured to fitinto an opening on the guidewire coupler 242 so that the guidewire canbe pulled distally from outside of the patient. In some variations thedistal end of the device may be completely withdrawn, so that it can begrasped and manipulated. In other variations, the distal end of thetissue-modification device remains coupled to the guidewire, and theguidewire may be grasped to manipulate the distal end of thetissue-modification device. A handle may be attached to the guidewire.

The overall tissue-modification device shown in FIG. 2A has an elongatebody formed of the plurality of substantially rigid rungs. Thisvariation has a length (an axial length, from proximal to distal) and awidth. The length of the device is longer than the width of each rung.In some embodiments, the ratio of the length of the device to the widthof each rung is greater than five. Alternatively, in some embodiments,the ratio may be greater than ten. The device is also relatively thin;in this variation the thickness is smaller than the width of each rung.In some embodiments, the ratio of the width of each rung to thethickness of each rung is greater than two. Alternatively, in someembodiments, the ratio may be greater than five. The use of two cablesfor the device shown in FIG. 2A allows the articulation of the links.

The distal end of the device 235 (including the guidewire couplerregion) is hinged, as is the connection to the proximal end 252. In somevariations the couplings at the proximal and distal regions allowrotation of the connection with respect to the tissue modificationregion such that torque (twisting motion) is not transferred to thetissue modification region. For example, FIG. 3A illustrates onevariation of the distal end of the tissue modification device in whichthe distal end includes a guidewire coupler 237 that is rotatablyconnected to the tissue modification device, more specifically to cable201, by connector 301. Alternatively, the distal end, including aguidewire coupler, may be rigidly attached to the cable, as shown inFIG. 3B. The distal ends of the cable include rungs 206 (as shown inFIG. 2A), protector portion, or links that cover the cable, and may helpprevent damage to tissue by presenting a relatively atraumatic surface.

In FIG. 2A, the flexible portion of the device formed by connected rungsor links is joined to the proximal end of the device, which may be lessflexible, and may include a handle or an attachment region for a handle.This interface between the links forming the flexible region and theproximal end is shown as joint 252. The proximal joint 252 near theproximal end 233 is a ball joint 207 to which the cables are attached.The ball joint allows the rotation of the handle and/or proximal portionof the device with respect to the tissue modification region of thedevice. Thus, the proximal handle may be rotated along the long axis ofthe tissue modification device, but will not substantially torque thetissue modification region of the device.

The variation shown in FIG. 2A may also include a proximal connectingregion 262 near the proximal end 233 of the device to which the handle231 is attached. This connecting region may be relatively stiff (orinflexible), or it may also be flexible.

As mentioned, in operation, the device is urged against the targettissue and may be moved in the proximal/distal direction to modify(e.g., cut) the target tissue. For example, both the proximal and distalends of the tissue-modification device may be pulled to urge the deviceagainst the target tissue, and may each be alternately pulled to agreater degree than the other handle to slide the device over the targettissue, allowing the cutting edges to cut and modify the target tissue.In this example, as the blade(s) cut the tissue, a moment is generatedbetween the tip of the blade and the base of the blade, on the rung,where the cable runs through the rung. Thus, in some variations, thebase of the blade rung must be sufficiently wide to resist rotatingabout the length of the cable. Furthermore, it may be advantageous toinclude fixed rigid sections.

As mentioned, the rungs forming the device may be flexibly connected byhinges between the rungs. The connections shown in FIG. 2A are flexibleconnections, and individual rungs are not directly connected, but areinstead connected via a cable. Since the cable is flexible, the flexionpoint is concentrated between rung and mating ferrule (spacer).

FIG. 4 shows a portion of a tissue modification device similar to thatshown in FIG. 2A. In FIG. 4, the cutting rungs each include a pluralityof cutting edges. These cutting edges are again shown as oriented alongthe long axis of the device, although other orientations may be used.The cutting edges may be offset from each other along the long axis ofthe device, so a wider cutting area is formed. In addition the cuttingedges may be spaced from the sides of the rungs, allowing the edges ofthe tissue modification device to be relatively atraumatic. FIG. 4 alsoillustrates spacers between each rung or link, on either side of thedevice (i.e., on each of the cables). In FIG. 4, different spacers areshown, including relatively long ferrules 401, and bead-like spacers403. The different spacers may modify the flexibility of the device.

FIG. 5A illustrates a portion of the proximal end of the tissuemodification device shown in FIG. 2A in which the cables are attached tothe joint 207 by coils 501 that permit the cables to flex duringoperation. In some variations, these coils may be springs.

In some variations, as shown in FIG. 5B, the rungs forming the devicemay be flexibly connected by hinges between the rungs without spacers.The connections shown in FIG. 5B are flexible connections. Individualrungs are not directly connected, but are instead connected via a cable.Since the cable is flexible, the flexion point is concentrated betweeneach rung. The length of each rung may be designed such that everytransition point between each rung is a hinge point. As shown in FIG.5B, the rungs may be configured such that a pair of rungs defines anopening between them. This opening may provide a location through whichtissue may travel and/or be collected.

In some embodiments, as shown in FIGS. 6-8A, a tissue-modificationdevice may include flexibly connected rungs or links that do not requirethe connection by a proximal-distal cable illustrated in FIG. 2A. Forexample, FIGS. 6-8A show various methods of flexibly connecting rungs orlinks. In FIG. 6, two adjacent cutting rungs are joined together so thatthey may move relative to each other as the device is flexed. In thisexample the devices are hinged. FIGS. 7 and 8A illustrate alternativevariations similar to FIG. 6. In FIGS. 6-8B, the adjacent rungs or linksare directly connected to each other and can be bent or moved asillustrated by the arrows. As shown in FIG. 8B, the devices can be bent(at least partially). In FIG. 8B, the hinged region may be formed bybending two regions of the adjacent links over each other. In thesevariations, a separate connector (e.g., cable, etc.) is not necessary toallow adjacent links to flex. Alternatively, the hinged regions mayinclude a hinge pin (not shown).

FIGS. 9A-9D illustrate another alternative method of connecting adjacentrungs or links to allow flexion or provide flexibility. FIGS. 9A-9D showan embodiment in which adjacent links are connected via a woven ribbonto which the rungs are secured. A portion of flexible material is shownin FIG. 9A. Any appropriate (flexible) material, including meshes,woven, non-woven, and polymeric materials may be used. For example, theflexible material could be made from several materials, for example:stainless steel, aramid fibers, carbon fibers, glass fibers etc. Rungscan be attached to the flexible material by any appropriate method. Forexample, FIG. 9B shows a rung having downward-pointed edges configuredto either pierce the woven ribbon or to be bent around the connectormaterial, as illustrated in FIGS. 9C and 9D. The bottom side of thematerial and/or rungs can be softened by molding a polymer 904 to thematerial, as illustrated in FIG. 9H. The material may be formed into aribbon or band shape. Additional rungs (of different or similardimensions), may also be secured to the connector material forming thedevice.

FIGS. 9E and 9F show another variation in which the downward-pointededges of the rungs penetrate the material and pass through it so thatthey can be and secured to it. For example, In FIG. 9E, the downwardpointing edges pierce the material (though the material may also includepre-formed holes). The downward-pointed regions can then be bent back upto secure the rung to the connector material. Other means for fasteningthe rung to the connector material may also be used. In the exampleshown in FIGS. 9E-9G, the edge of the rungs is not concurrent with theedge of the tissue-modification device. FIG. 9G shows a portion of anexemplary tissue-modification device including a flexible connectorconnecting multiple rungs having cutting edges extending from them. InFIG. 9, the rungs are spaced from the edge of the tissue cutting device,and an atraumatic edge 903 is included along the outer periphery (alongthe major surface).

Spacing the rungs from the edge in this manner may reduce the risk ofside cutting. Other variations, including variations having a connectorcable(s), the cable and rungs can be protected on the side by a separatetube like elements on the edges that are interlaced with the rungs andthe cable, as illustrated in FIGS. 10 and 11. In FIG. 10, for example,the cables 1001, 1001′ on either sides of the device are covered by aprotective cover 1003. Rungs 1005 span the distance between the twocables. FIG. 11 shows a slightly higher magnification of the tissuemodification region of the device shown in FIG. 10. In FIG. 11, thecutting edges 1101 are shown extending from the rungs.

Fixed Tissue Capture Region

The blade rung “ladder” design described above for the tissuemodification devices having flexibly linked rungs may include spacesbetween the rungs. In some variations the tissue cutting region may alsoinclude holes or openings. These spaces between the rungs, holes, and/oropenings may form part of a tissue capture region, or may act as vias orchannels to direct cut tissue into a tissue capture region. As thetissue modification region modifies and/or removes the tissue, at leasta portion of (and preferably the majority of) the cut tissue may belodged between the cutting edges or blades and/or between the rungs ofthe device, such that the captured tissue is removed from the patientalong with the device as the device is removed from the patient.Alternatively, in some variations, the space between the rungs maychannel cut tissue into a tissue capture region. As the cutting edges(e.g., the triangular “teeth” shown in some of the figures, above) cutthe tissue, the tissue may be driven into a tissue capturing orcollection region. In some variations, the edge of the adjacent rung mayshear the tissue as the device is urged against the tissue and moved. Insome variations, the edge of the rung may also be sharp, or may includea sharp region. Thus, tissue may pass through the blade rungs and into atissue collection region. The (typically upward) pressure of urging thedevice against the target tissue may therefore aide in packing thetissue into a tissue capture region. In some embodiments, the device mayhave elements to aid in the movement of the cut tissue. For example, therungs may be designed such that two adjacent rungs function as a one wayvalve, allowing the tissue to enter through the space between the rungs,and then kept between or below the rungs and prevented from moving backout. Each rung may include a flap or a wing that couples to a flap orwing of an adjacent rung to function as a one way valve. The rungs mayalternatively be designed in any other suitable fashion.

In general, a tissue capture region may require some amount of force orpressure to drive the cut tissue into the capture region. This may beparticularly true for expandable tissue capture regions, such as anexpandable bag that is attached behind the tissue modification region(e.g., behind or within the rungs including cutting edges). As thetissue fills the area below the blades, the bag may expand toaccommodate the increase volume. Increased pressure may be required to‘pack’ the tissue into the tissue cutting region.

In some applications it would be beneficial to provide pre-expandedtissue capture regions, or tissue capture regions having a minimumvolume that is fixed. The fixed minimum volume typically refers to afixed open volume. Fixed minimum volume tissue capture regions typicallyinclude a minimum open volume, but this open volume may be increased asthe device is operated; for example, the volume may be expandable fromthe fixed minimum open volume. Alternatively, the total volume of thetissue capture region maybe fixed or predetermined. Having a fixedminimum open volume allows tissue to enter the tissue capture regionwithout having to apply additional force to drive the tissue into thetissue capture region.

In some variations a tissue collection region having a fixed minimumopen space may be defined by the space between the openings into thetissue collection region (which may be the rungs of the tissuemodification region) and a tissue collection substrate. The tissuecollection substrate is typically spaced apart from the tissuemodification side of the rungs by a thickness that forms the open space.The tissue collection region may have a length that extends at leastalong the tissue modification region of the tissue modification device(e.g., the cutting rungs in variations including rungs), but may extendfurther proximally/distally.

For example, FIGS. 12A-12C illustrate one variation of a tissuemodification device including a tissue collection region having a fixedminimum open space. FIG. 12A shows a cross-section along the long(distal/proximal) axis of the device. In this variation the deviceincludes a plurality of flexibly connected rungs 1205 that are connectedby a connector (a cable 1215). The rungs in the tissue modificationregion include cutting edges 1209. A tissue collection region 1219(illustrated in FIG. 12B) is formed between the top of the rungs 1205and a tissue collection substrate 1211. In this example, the tissuecollection substrate 1211 is a semi-rigid substrate element that extendsalong the proximal/distal length of the device. In some embodiments, thesubstrate element may additionally include guiding features to moveand/or position the tissue in a desired direction, such as toward theouter portions of the device, beneath the non-cutting rungs. Forexample, a guiding element may be one or more ridges in the substratethat are arrow or chevron shaped, with the vertex of the shape pointedtoward the outer regions of the device. The distal end of this variationalso includes a guidewire coupler or coupling region 1252, andindividual links 1205 may be separated by spacers (shown as ferrules)1245.

FIG. 12B shows a cross-section through one of the rung elements 1205shown in FIG. 12A. In this variation, the rung 1205 includes twochannels 1216 and 1216′ through which the cables 1215 (FIG. 12A) maypass. The top (anterior) of the rung includes a plurality of cuttingedges 1209. Within the rung 1205 is a fixed open volume 1219 that isformed between the top of the rung and a tissue collection substrate1211 on the bottom of the rung. The tissue collection substrate may besecured within the rung by loops or straps 1223 that extend across thebottom of the rung. FIG. 12C shows a top view of the tissue modificationdevice of FIGS. 12A and 12B.

The tissue-collection substrate portion of the tissue modificationdevice shown in FIGS. 12A-12C is slideable within the rungs (e.g., alongthe straps of the rungs). One end of the tissue collection substrate maybe fixed (e.g., near the distal end of the device) and the other end mayinclude an elastic or spring element 1272 that allows thetissue-collection substrate to slide as the tissue modification deviceis bent during operation. FIGS. 13A-13D illustrate variations oftissue-collection substrates that may be used. For example, in FIG. 13A,the tissue collection substrate 1211 is a semi-rigid sheet of materialas shown in FIG. 12A-12C. The tissue-collection substrate may be formedof any appropriate material, including metals or alloys (e.g., stainlesssteel, titanium, NiTi, aluminum, etc.), plastics (e.g., PEAK, PET, PP,EP, PET, etc.), and elastic materials (e.g., urethanes, silicones,etc.). Other materials may also be used. Since the overall device(including the tissue collection substrate) is flexible at least in theplane forming the major surfaces, the tissue collection substrate may bebendable. Thus, when more rigid materials are used (e.g., metals) toform the substrate, the substrate may be relatively thin.

FIGS. 12D-12G illustrate another variation of a tissue modificationdevice including a tissue collection region having a fixed minimum openspace. FIG. 12D shows a perspective view of a portion of a tissuemodification device including a tissue collection region 1262. Thistissue collection region has sides and a bottom region, and includes achannel through which connectors (shown as cables 1266, 1266′ in FIG.12D) may pass. The tissue collection region may be a single, flexiblepiece, as indicated in FIG. 12D, or it may be a plurality of pieceslinked by the connector. In this variation, the tissue collection regionalso includes spaced into which rungs may fit so that the connectors maypass through the rungs. This is also apparent from the top view shown inFIG. 12E. FIGS. 12F and 12G illustrate sectional views taken through aportion of the tissue modification device including a cutting run (shownin FIG. 12F) and a portion of the tissue modification device that isbetween adjacent cutting rungs (shown in FIG. 12G).

Alternatively, the tissue collection region may include projections thatproject into a space or slot formed on the rungs; the connectors maypass through these projections and through the rungs. IN addition,spacers (e.g., ferrules, beads, etc.) may be used between the rungs.

In some variations, the substrate may be configured to expand/contractas the tissue modification device is flexed. For example, as describedabove, in some variations the tissue collection substrate may beconnected at one (or both) axial ends via a spring or elastic member.FIGS. 13B1 to 13B3 illustrate a side view of another variation of asubstrate that is configured to accordion along its length as the deviceit is attached to is flexed. For example, when the tissue modificationdevice is flexed or bent in a first direction the substrate may contractor accordion closed, as shown in FIG. 13B1. In the relaxed state thesubstrate is ‘neutral’, with folds that may be expanded or contracted,as shown in FIG. 13B2. When the tissue modification device is bent in asecond direction the substrate may expand or accordion open, as shown inFIG. 13B3.

In an alternative variation the substrate is expandable, and includesrigid edge with an expandable element between, as illustrated in FIG.14A. In this variation the rigid portion may be secured to the tissuecollection device (e.g., to the links of a tissue collection device),and the expandable portion may be made of a mesh or thin plasticmaterial. FIG. 14B shows just the rigid portion of one variation of thisembodiment, in which the rigid frame 1401 surrounding an expandableportion 1403 includes cross-struts 1407. Substrates including expandableregions may be useful to allow the tissue collection region to expandeven beyond the minimum fixed volume, allowing the collection ofadditional tissue even after the minimum fixed volume is filled.

In general, the tissue collection substrate may be held to the tissuemodification device by one or more connectors linking the tissuecollection substrate to the rung. In FIGS. 12A-12C the tissue collectionregion is bounded by the tissue collection substrate that is secured tothe link via a strap or loop that is formed by the rung. In somevariations the connectors are not part of the rungs, but are separateelements. For example, FIGS. 15A-15C illustrate variations in which thetissue collection substrate is secured to the device by a cable or rodconnector between each rung and the tissue collection substrate. In somevariations, the connector is formed as a part of the tissue collectionsubstrate. FIG. 15A shows a cross-section through a flexible tissuemodification device having rungs 1501 and a tissue collection region1509 that is formed between the top of the rung 1501 and a substrate1511 that is secured to the rung by a pair of cables 1515, 1515′ orrods. FIG. 15C shows a similar variation in which the substrate issecured to the rung by connectors that may swing or slide. As described,the rung shown may be flexibly connected via one or more cables 1503,1503′. In all of these examples of tissue collection regions there is aminimum open volume that has a fixed minimum, so that, even when flexed,the tissue collection region has a non-collapsible open space so thattissue can enter the space. In some variations this minimum fixed spaceis formed by a separation of between about 2 and about 6 mm between therung forming the top of the space and the substrate.

FIG. 15B shows a cross-section through the tissue modification region ofa tissue modification device including rung and tissue collection designshown in FIG. 15A. As before, the tissue collection substrate in thisexample is shown axially connected to the device via a spring 1511.

In operation, tissue cut by the blades may be collected into the tissuecollection regions described. As mentioned, openings between the rungsmay act as channels or vias through which cut tissue may pass into thecollection region(s). In some variations, the tissue modification devicemay include openings adjacent to the cutting edge(s) through whichtissue may pass. Although the examples described above include tissuecollection regions having a fixed minimum open volume as part of atissue modification device comprising a plurality of rungs, a fixedminimum open volume tissue collection region may be incorporated as partof any tissue collection region, even those not having rungs.

Other examples of tissue capturing mechanisms which may be used aredescribed, for example, in U.S. U.S. patent application Ser. No.11/687,558, filed Mar. 16, 2007, titled “FLEXIBLE TISSUE REMOVAL DEVICESAND METHODS,” now U.S. Pat. No. 8,062,298; U.S. patent application Ser.No. 11/687,548, filed Mar. 16, 2007, titled “TISSUE REMOVAL WITH ATLEAST PARTIALLY FLEXIBLE DEVICES,” now U.S. Pat. No. 8,062,300; and U.S.patent application Ser. No. 11/952,934, filed Dec. 7, 2007, titled“TISSUE REMOVAL DEVICES AND METHODS,” Publication No.US-2008-0147084-A1, now abandoned; these references are all incorporatedby reference herein in their entirety.

As mentioned above, the spacing and orientation of the cutting edges ofthe tissue modification devices may be arranged to optimize performance.For example, FIG. 16A to 16C illustrate one arrangement of cutting edges(blades) in which adjacent rungs have blades that are offset from eachother. Offsetting the blade in this manner may allow them to moreuniformly cut as the device is operated to modify tissue. Blade densitymay be important when it comes to cutting both soft tissue and bone. Toimprove the density and allow for material to pass through blade teeth,the leading and following blades may be interdigitated. FIGS. 16A-16Cshow the interdigitation of a set of blades. The first rung 1601(Rung-A) cuts a leading path and the second rung 1603 (Rung-B) cuts afollowing path. This arrangement of cutting edges and rungs may helpmaximize the material removal for one cut stroke. FIG. 16C is a sideview of Rung-A directly in front of Rung-B.

Non-Linear Shapes and Shape Morphing

In addition to the substantially linear tissue modification devicesdescribed above, any of these tissue-modification devices may also beconfigured to have a non-linear shape (e.g., axial shape) and/or beshape-morphing devices that can convert between linear and non-linearshapes. Non-linear devices may be pre-formed into a curved or bent shape(such as “s”-shaped, or serpentine, device or “c”-shaped devices, or thelike). Alternatively, a non-linear device may be a shape-morphing devicethat can be changed from a linear to a non-linear shape, either beforeor during use of the device to modify tissue.

The phrase ‘linear’ and ‘non-linear’ shapes typically refer to the shapeof the device along the major (distal/proximal) axis, when looking downon the major (tissue-modifying) surface.

For example, FIG. 17A illustrates a device having an S-shape (orserpentine) shape. This is a non-linear device (since the major surfacedoes not travel in a line, but is curved). The device can be constructedusing the cable (or wire) rung design, as illustrated in FIG. 18. InFIG. 18, the links are separated by one or more spacers that are unequalin length from one side of the device (e.g., one cable) to the other.This difference in spacing causes the device to curve, as shown. Forexample, the side of a device with a larger radius of curvature mayinclude spacers such as relatively long ferrules 401 (shown in FIG. 4),and the side of a device with a smaller radius of curvature may includebead-like spacers 403 (shown in FIG. 4). Curved devices may have a widerstroke length when cutting the tissue, and may therefore cut a widerregion of tissue. For given stroke length, the amplitude (peak to peakof the curve) becomes the effective width of the device, producing akerf wider than the individual rung.

Additionally the devices can be deployed into the spine in a linearconfiguration and then changed to a non linear configuration. Thisconversion in shape may be achieved in-situ by pulling on a cable on oneside of the rung more than the other side. Alternatively, you can pullboth sides with the same tension in combination with variablycompressible ferrules/spacers between the rungs in selected locations.For example to achieve a concave curve to the device on the right side,the right side would have more compressible ferrules (elastomeric) thanthe left side. Once the new non-linear shape was achieved, the cablewire(s) could be locked in position near the proximal end and/or handle.If desired, the cables could be readjusted to form a linear shape to thedevice prior to device removal. For example, a device may be increasedin width by shift parallel links from an oblique angle to perpendicularwith the cable, shown in the images below.

In some variations, the shape-morphing devices may be transitionedbetween a first straight (e.g., linear) configuration and a secondstraight configuration, with the first configuration being narrower thanthe second configuration. Two examples of this are shown in FIGS.17B-17C and 17D-17E. In FIG. 17B the tissue modification device has arelatively narrow profile and can be expanded into a wider profile asillustrated in FIG. 17C. The rungs in FIG. 17B are initially diagonal,relative to the parallel cables flexibly connecting them. By pulling onone of the cables, one side of the device to which the rungs areconnected, may be pulled to align the rungs perpendicular to the longaxis of the device. Since the rungs are relatively rigid, this willexpand the width of the tissue modification device, as indicated in FIG.17C.

FIGS. 17D and 17E illustrate a similar variation, in which the tissuemodification device may be expanded from a first linear configuration,in which the rungs are chevron-shaped when viewed from the top as inFIG. 17D, to a second linear configuration that is wider, in which therungs can be pulled so that they are perpendicular to the long axis(proximal/distal axis) of the device, as illustrated in FIG. 17E. Inthis variation, a cable, pull wire, or the like may be connected to therungs to convert them from the first to the second shapes. The rungs maybe adapted (e.g., hinged) for conversion. In some variations each run isactually a two rungs that are joined end-to-end.

Any of the tissue modification devices described herein may be used todecompress one or more spinal regions, as mentioned above. Inparticular, any of these devices may be used to decompress nerve rootsplaced within the spinal anatomy along various paths, including thoseshown in FIGS. 19A-19C. Because these devices are flexible, and may beappropriately sized and shaped to fit within a neural forman, thesedevices may be used to accesses appropriate regions of the spine from asingle access point (e.g., from the patient's midline or near-midlineregion). The procedure may be used to decompress spinal nerve roots onthe unilateral or bilateral side from the access point. A probe or guidemay be introduced into the spinal epidural space (or along or justwithin the ligamentum flavum) at an appropriate spinal level using imageguidance and/or tracking (e.g., electromagnetic tracking). Introductionmay be either via percutaneous puncture or open laminotomy.

As shown in FIG. 19A, the device may be used to decompress anipsilateral or contralateral proximal nerve (in a lateral recess). Aguide may be deployed immediately cephalad to the caudal segment pedicleon the appropriate side (e.g., location 1810). This access point can beconfirmed radiographically. If neural structures adjacent to the guidecannot be directly visualized, the relationship of these structures tothe guide or tissue modification devices can be determined usingelectrical stimulation, ultrasound imaging, endoscopic mean or othertechniques. In some variations, once the guide is deployed and optionalneural localization is complete, a guidewire is passed via thecannulated guide. The guidewire can be sharp on its distal end andpenetrate the skin dorsolaterally after exiting the foramen. Theguidewire may includes a wire exchange tip on its proximal end, asmentioned above. As shown in FIG. 19A, the guidewire may be threadedalong a path from location 1810 to where it exits through the foramen,as shown by at least one of arrows 1812 (for ipsilateral decompressionof the nerve root origin at the disk level) and 1814 (for contralateraldecompression of the nerve root origin at the disk level). In someembodiments, the probe/guide is removed once the guidewire has beenpositioned.

Next, a flexible tissue modification device is attached to the proximalwire exchange tip, and a distal handle may be secured to the distal wiretip. The device can then be introduced into the epidural space and theninto the lateral recess by careful upward force applied to the distalhandle. In some embodiments, the device is pulled by the guidewire onthe path through the spinal anatomy. As described above, suitable pathsinclude paths shown by arrows 1812 and 1814 to decompress the nerve rootorigin at disk level. Once the device is in place as confirmed visuallyor radiographically, bimanual reciprocating strokes may be utilized todecompress dorsal impinging bone or soft tissue at the nerve rootorigin. In some embodiments, approximately 30-40 reciprocating strokesare required to complete the decompression. This may be confirmedradiographically or with palpation by instruments. The device may thenbe detached and the wire removed.

The probe/guide may be reinserted to decompress the ipsilateral orcontralateral distal (foraminal) portion of the nerve root, so that thesame (or a different) tissue modification device may be used todecompress another region of the spine (or nerve root) using the sameaccess or entry site. Thus, a guide may be deployed immediately caudalto the caudal segment pedicle on the appropriate side. The guide may bedeployed in the same access point (location 1810) as described above.Transforaminal positioning and the relationship to neural elements canagain be confirmed visually, radiographically, and/or with electricalstimulation, ultrasound or alternative means. Once appropriatelocalization is confirmed, the guidewire can be passed and probe/guideremoved. As shown in FIG. 19A, the guidewire may be threaded along apath from location 1810 to where it exits through the foramen, as shownby at least one of arrows 1816 (for ipsilateral decompression along thenerve root) and 1818 (for contralateral decompression along the nerveroot). A handle is attached to the distal guidewire and the tissuemodification device to the proximal exchange tip. The device is thenintroduced into the spine (e.g., the epidural space, or the regionanterior to the posterior edge of the ligamentum flavum) with carefulupward force applied to the distal handle. In some embodiments, thedevice is pulled by the guidewire on the path through the spinalanatomy. As described above, and as shown in FIG. 19A, suitable pathsinclude paths shown by arrows 1816 and 1818 to decompress along thenerve root. The foraminal decompression is performed using bimanualreciprocating strokes to remove impinging bone and soft tissue. In someembodiments, approximately 30-40 strokes are required to decompress theroot. Confirmation of decompression may be done radiographically orusing instruments to palpate along the root. The device can then bedetached and the guidewire removed.

As shown in FIG. 19B, the devices described herein can used todecompress the ipsilateral or contralateral (not shown), or both,regions adjacent the level proximal to the nerve root (lateral recess).A guide may be deployed in the same access point (location 1810) asdescribed above. Transforaminal positioning and the relationship toneural elements are once again confirmed visually, radiographically,and/or with electrical stimulation, ultrasound or alternative means.Once appropriate localization is confirmed, the guidewire may be passedand the probe/guide removed. As shown in FIG. 19B, the guidewire canthen be threaded along a path from location 210 to where it exitsthrough the foramen, as shown by arrow 220 (for ipsilateraldecompression of the adjacent nerve root origin). A handle can beattached to the distal guidewire and the guidewire can then be attachedto the distal end of one of the tissue modification devices describedherein. The device can then be introduced into the spine by pulling onthe guidewire. In some embodiments, the decompression device is pulledby the guidewire on the path through the spinal anatomy as illustratedin FIG. 19A, 19B, or 19C. As described above, and as shown in FIG. 19B,suitable paths include the path shown by arrow 1820 the adjacent nerveroot origin. The lateral recess decompression may be performed usingbimanual reciprocating strokes to remove impinging bone and soft tissue.In some embodiments, approximately 30-40 strokes are required todecompress the nerve. Confirmation of decompression may be doneradiographically or using instruments to palpate along the root.

As shown in FIG. 19C, a probe/guide may be used to introduce a tissuemodification device as described herein to decompress the central canal.The guide may be deployed in the same access point (location 1810) asdescribed above. Once appropriate localization is confirmed, theguidewire may be passed and probe/guide removed. As shown in FIG. 5, theguidewire can be threaded along a path from location 1810 to where itexits through the intralaminar window, as shown by arrow 1822 (not theadjacent foramen). A handle may be attached to the distal guidewire and,the tissue modification device may be coupled to the proximal end of theguidewire. The device can then be introduced into the epidural space bypulling the distal end of the guidewire on the path through the spinalanatomy, drawing the device into position adjacent the target tissue inthe spinal canal. As described above, and as shown in FIG. 19C, suitablepaths include the path shown by arrow 1822 to decompress tissueassociated with the central canal and may be effective in treatingpatients with central spinal stenosis. The decompression may beperformed using bimanual reciprocating strokes to remove impinging boneand soft tissue. In some embodiments, approximately 30-40 strokes arerequired to decompress the root. Confirmation of decompression may bedone radiographically or using instruments to palpate along the nerve.

In some embodiments, the probe, guide, or guidewire may also include atracking element or plurality of tracking elements. The tracking elementmay be similar to the tracking element of the tissue modificationdevice. As described above, in some embodiments the tracking element isa material that is detectable by an imaging system, while in someembodiments the tracking element is preferably a coil configured to bedetected by an electromagnetic tracking or navigation system.

Any of the procedures described herein can be done in combination withother techniques including an open or minimally invasive decompressionprocedure where tools such as rongeurs and powered drills are used toremove tissue primarily around the proximal end of nerve root (lateralrecess). Such techniques may include laminotomies, etc.

Although various illustrative embodiments are described above, any of anumber of changes may be made to various embodiments without departingfrom the scope of the invention as described by the claims. For example,the order in which various described method steps are performed mayoften be changed in alternative embodiments, and in other alternativeembodiments one or more method steps may be skipped altogether. Optionalfeatures of various device and system embodiments may be included insome embodiments and not in others. Therefore, the foregoing descriptionis provided primarily for exemplary purposes and should not beinterpreted to limit the scope of the invention as it is set forth inthe claims.

What is claimed is:
 1. A method of modifying tissue, the methodcomprising: passing a guidewire at least partially around the targettissue; and pulling a flexible tissue-modification device having atissue collection region around the target tissue using the guidewire,wherein the flexible tissue-modification device comprises: a flexibleelongate body having a width and a thickness and a plurality of parallelrungs extending perpendicularly transverse to the proximal and distalaxis, each attached to the flexible elongate body, wherein a baseportion of each rung is detached from the base portion of each otherrung and extends at least partially across the width of the body,wherein the rungs being detached from each other forms gaps betweenadjacent pairs of rungs, and at least one cutting edge on two or more ofthe rungs, and wherein the tissue collection region opens within the gapallowing tissue to enter through the gap between the rungs and keptbetween or below the rungs and prevented from moving back out; movingthe tissue-modification device against the target tissue by pulling thetissue-modification device from at least one end of the device; cuttingthe target tissue with the cutting edges on the rungs of thetissue-modification device; and collecting the cut tissue in the tissuecollection region by packing the cut tissue between and below the rungs.2. The method of claim 1, further comprising collecting cut tissue intoa tissue collection portion of the tissue-modification device.
 3. Themethod of claim 1, wherein the target tissue comprises tissue within aspinal foramen.
 4. The method of claim 1, wherein the step of moving thetissue-modification device against the target tissue comprises applyingtension to both the proximal end and the distal end of thetissue-modification device to drive the tissue-modification deviceagainst the target tissue.
 5. The method of claim 1, further comprisingthe step of detecting neuronal tissue near the flexibletissue-modification device.
 6. A method of removing tissue from apatient, the method comprising: passing a flexible tissue-modificationdevice having a tissue collection region at least partially around atarget tissue, wherein the flexible tissue-modification devicecomprises: a flexible elongate body extending in a proximal to distalaxis along a length, the elongate body comprising a plurality ofparallel rungs extending perpendicularly transverse to the proximal anddistal axis, the elongate body having an anterior surface including theanterior surface of the rungs, and a plurality of cutting edgesextending from the anterior surface of the rungs, wherein a base portionof each rung is spaced away from the base portion of each adjacent rungthereby forming a gap between the base portions of adjacent rungs of theplurality of rungs, wherein the base portion of each rung is attached toa flexible substrate of the elongate body, and wherein the tissuecollection region opens through the anterior surface within the gapsbetween the base portion of adjacent rungs of the plurality of rungsallowing tissue to enter through the gap between the rungs and keptbetween or below the rungs and prevented from moving back out; movingthe tissue-modification device against the target tissue by pulling thetissue-modification device from at least one end of the device; cuttingthe target tissue with the cutting edges; and collecting the cut tissuein the tissue collection region by packing the cut tissue between andbelow the rungs.
 7. The method of claim 6, wherein the step of passingthe flexible tissue-modification device at least partially around thetarget tissue comprises: passing a guidewire around the target tissue;and pulling the flexible tissue-modification device around the targettissue using the guidewire.
 8. The method of claim 6, wherein the targettissue comprises tissue within a spinal foramen.
 9. The method of claim6, wherein the step of moving the tissue-modification device against thetarget tissue comprises applying tension to both the proximal end andthe distal end of the tissue-modification device to drive thetissue-modification device against the target tissue.
 10. The method ofclaim 6, further comprising the step of sensing neuronal tissue near theflexible tissue-modification device.